Pneumatic needle-bar positioner for sewing machines



R. H. HALL March 27, 1962 PNEUMATIC NEEDLE-BAR POSITIONEIR FOR SEWINGMACHINES Filed March 31, 1958 5 Sheets-Sheet l INVENT OR. RichardH.Ha1l,

AT TOENEY.

March 27, 1962 R. H. HALL 3,026,835

PNEUMATIC NEEDLEBAR POSITIONER FOR SEWING MACHINES Filed March 31, 1958Sheets-Sheet 2 I 55 15b 51a 1 21a 27 125 21 P510 293 45 9 '59 27a 27a 15Fig. 4 /3 29' 58 57c I "A 37b 452 4? 57' 57a *9 a INVENTOR:

RicharAH. Hall,

BY wax flaw ATTORNEY March 27, 1962 R H 3,026,835

PNEUMATIC NEEDLE-BAR POSITIONER FOR SEWING MACHINES Filed March 31, 19585 Sheets-Sheet 3 66 INVENTOR.

Rlchard Hfiall,

BY WW @LJM AT TORNFYT United States atent 3,026,835 PNEUMATIC NEEDLE-BARPOSHTIONER FOR SEWING MACHINES Richard H. Hall, 3907 Estes Road,Nashville, Tenn. Filed Mar. 31, 1958, Ser. No. 725,021 8 Claims. (Cl.112-221) This invention relates to a pneumatic needle-bar positioner forsewing machines.

More particularly the invention pertains to pneumatically operated meansfor positively positioning the needle bar of a sewing machine in apredetermined position (usually up but selectively down if preferred) atthe end of each sewing operation involving raising of the presser foot,said means being constructed and arranged to forwardly rotate the shaftreciprocating the needle bar thru an angle approaching 350 deg. (orbackwardly about deg.) to prevent undesirable slack in the threads (asoccurs in needle positioners which produce half of the time backwardrotations up to 180 deg).

3,026,835 Patented Mar. 27, 1932 'drivingly connected to shaft by anautomatically op- This disclosure is an improvement over applicantspreviously filed application S.N. 610,362, filed September 17, 1956, forMeans Responsive to Sewing-Machine Presser-Foot Operation forWork-Control Positioning of Needle Bar, the disclosure of which ishereby included herein by reference. 'Its purposes are fundamentally thesame as those of said prior application, namely automatic positivepositioning of the needle in predetermined position relative to the workwhen the presser foot is raised and for the reasons stated therein, butit advantageously differs therefrom in providing pneumatic operatingmeans in place of knee-powered means and in very desirably providing upto 350 deg. forward rotation of the needle-bar-driving shaft, thusleaving only an occasional (1 in 36) backward rotation of 10 deg. orless, which does not produce an objectionable thread slackening, ascompared with the 180 deg. backward rotation of priorart needle-bar positioners.

It is accordingly the principal object of this invention to provide aneedle-bar positioner in which threadslackening (backward) movementthereof is reduced to a minimum both in frequency and in amount ofmovement.

It is a further object to provide such a device with pneumatic operatingmeans.

It is a further object to provide such a device with automatic clutchmeans for disconnecting the belt-driven pulley from the hand-wheelshaft.

These and other objects and advantages of the invention will becomeapparent as the following detailed description proceeds.

In the drawings:

FIG. 1 is a perspective view of a preferred embodiment of the invention.

FIG. 2is a front elevational view of the unenergized device of FIG. 1 inpartial axial section.

FIG. 3 is a view similar to FIG. 2 showing the pants pneumatically movedto needle-positioning positions.

FIG. 4 is a view, similar to FIG. 2 of a modified construction.

FIG. 5 is a perspective view of the automatic air valve.

FIG. 6 is an enlarged elevational view of the valve in vertical sectiontaken on the plane of the axes of the tapped air inlet and outletpassages.

FIG. 7 is a view similar to FIG. 6 but showing the valve parts indevice-operating positions.

With reference now to FIGS. 1 and 5, the numeral 11 designates the baseof a conventional factory-type sewing machine which rests upon machineboard 12 and from which rises the overlying hollow head member 13.

erated clutch mechanism which permits the pulley 19 to free-wheel whenthe needle positioner is in operation.

The automatic clutch mechanism comprises the hand wheel 21 which iskeyed to the shaft 15 for limited axial movement thereon. A compressionspring 23 acting between flange abutment 15a and washer 21a normallyforces wheel 21 to the left (FIGS. 2 and 3) so as to grip the pulley 19between the two clutch disks 25 and 26.

Disk 26 is held against axial movement away from pulley 1? by the flange27 fixed to the extension 15b of the hand-wheel shaft 15 by its integralhub 27a upon which the pulley 19 free-wheels when declutched.

The pneumatic operator comprises the shaft extension 15b rigidly coupledto shaft 15 and in accurate alinement therewith, and the pneumaticcylinder 29 concentrically mounted there around. Cylinder 29 is providedwith an enlarged extension sleeve 29a slidably mounted in the supportblock 31 and keyed thereto at 31a. Block 31 is formed of two partsconnected by screws 31b. Block 31 is accurately and adjustablypositioned and held against rotation by the rigid structure consistingof screws 32 and 33 adjustably connected to block 34 by nuts 34', thearticulated arm 35, and the anchor post 36 fixed to the base portion 11.

The flexible hose 3'7 conducts compressed air to cyl-' inder 29. Airenters thru passage 39a in the cylinder head 39. A pair of 0 rings 40and 41 of resilient material seal the joints between the head and thecylinder 29 and between the rotating shaft 15b and its embracing borethru head 39. A U-gasket 43 of resilient material forms the sealingportion of the annular piston completed by the flange 45a on thesleeve-cam 45. A spring 47, compressed between flange 45a and guide ring49 for the sleeve-cam 45, normally holds the parts in their FIG. 2positions. When compressed air enters port 39a it moves sleevecam 45 tothe left so that its 350 deg. heiical edge 45b engages a roller-bearingcam follower 51 to rotate the shaft 15-15b thru an angle up to about 350deg. in the forward direction. A pin 53 (fixed to guide ring 49) isengageable against the straight-edged face 45c of the cam 45 andprevents the free-floating sleeve cam 45 from being rotated bycam-followerexerted counter force. Follower 51 is mounted on post 51ascrewed into a radial bore in shaft 15b. The outer end of shaft 15b isjournaled in the bearing sleeve 55 mounted on the head 57 fixed to theend of cylinder extension 29a. If the par-ts are in the positions ofFIG. 2 whenthe air pressure is applied, the sleeve 45 will not movefollower 51 since its wedge-shaped end will not be forced between it andpin '53. Rather, the sleeve 45 will be moved away from pin 53 byfollower 51 until pin 53 is engaged by surface 45b near the socket 45d.Then the sleeve 45 will be rotated backwardly and will move the shaft,thru follower 51, about 10 deg. backwardly (which will not move theneedle bar appreciably, since it is in this case adjacent the bottom ofits stroke).

Since cylinder 2.9-29a is mounted in block 31 for slight axial movement,air pressure causes the same to move to the right (FIGS. 2 and 3) thusproducing clutchoperating engagement of pins 59 by the head 39. Pins 59are slidably received in bores thru the hub 27a.

The automatic control mechanism is illustrated in FIGS. 5-7. Saidmechanism comprises a clamp 61 consisting of a pair of plates 61a and61b having mating semicylindrical channels in their opposed faces whichclose upon and grip the conventional presser-foot operating rod 63 whenthey are drawn together by screws (not visible) the heads of which lieagainst the far side of plate 61a. The lower half of plate 61b carriesthe valve block 65 fastened thereto by the screw 66. Compressed air isfed to block 65 by the hose 67 and conventional coupling elements 68-70.A valve plunger 71 has a protruding operator 71a engageable against thetop of base 11. when the presser-foot operating rod 63 is depressedtoraise the presser foot. This operation raises valve disk 71b away fromthe sealing O-ring 72 to permit compressed air to flow into chamber 65aand thence thru couplers 7375 into the cylinder 29. When the rod 63 israised to lower the presser-foot into sewing position, valve stem 71drops to its FIG. 6 position shutting off the supply of compressed airand discharging that in the cylinder 29 thru ports 65b so that theneedle-bar-positioning cam 45 can be returned to its inoperativeposition of FIG. 2 by spring 47.

In the modification of FIG. 4, simplified by the omission of the clutchmechanism of the previously described species, the arrangement andactions of the parts are reversed. The shorter shaft extension 15bsupports the near end of cylinder 29' thru its head 58 attached theretoby screws 58. A flange 15c engages a thrust bearing 59' backed up by thecollar portion of head 58 to prevent undue thrust against shaft 15b whenthe cam 45' is pneumatically thrust against the follower 51. The outerend of shaft 15b is journaled in a bore 57a in the end of member 57, theleft end of which is enlarged to form the other cylinder head and isattached to cylinder 29' by screws 60'.

The cam 45' freely slides over the outer surface of member 57 and isheld against unlimited rotation thereon by' the screw pin 53 which alsohelps locate and support the outercam-guiding ring 49 and the centrallylocated end of member 57'. A spring 47 compressed between the flange 45aand guide ring 49' normally holds the parts intheir FIG; 4 positions.The cylinder 29' is supported by means equivalent to the parts 3136previously described but not slidable therein since the clutch-operatingmovement of the cylinder is not needed in this species. Bore 570' is anoiling port.

Compressed air enters cylinder 29 thru a port 57b connected by couplers37a and 37b to hose 37, which in turn is connected to an automaticvalve, such as 6175 previously described. The entering air forces the U-gasket 43 against cam flange 45a to rotate the'shaft 15b by engaging thefollower 51 and pin '53 as in the firstdescribed species.

While I have described a preferred embodiment of my invention it is tobe understood that many changes can be made in the size, shape,composition and arrangements of the partsiwithout departing from thespirit of the invention asdefined by the subjoined claims. For examples,the cam-thrusting means could be solenoid or human-powered (.by knee,hand, foot, etc.); or a manually or foot-operated switch or valve couldbe substituted for the automatic valve disclosed.

Having thus described my invention, I claim:

. 1. Means for positioning the needle bar and thereby the needle of asewing machine in a preselected stroke position, comprising: a cammember and a cam-follower member having normally disengaged surfacesproviding when said surfaces are engaged relative rotation in onedirection therebetween closely approaching 360", means operativelyconnecting one of said members for rotation with the needle-bar driveshaft of a sewing machine, and power-applying means for operating theother of said members into engagement with said one member to positionsaid needle bar in said preselected position by turning said needle-bardrive shaft in most instances in a forward direction to minimizefrequency of occurrence and amount of undesirable backward movement ofsaid shaft.

2. Structure according to claim 1, said power-applying means beingcoupled to presser-foot-operating mechanism of said sewing machine forautomatic control thereof in response to operation of said presser foot.

3. Structure according to claim 2, said power-applying means being apneumatic cylinder and said coupling means being a valve mounted on theconventional operating rod for said presser foot and operated inresponse to movement of said rod.

4. Structure according to claim 1, said power-applying means being apneumatic cylinder alined with an axial extension of said needle-bardrive shaft, said cam member being a sleeve operated by the piston ofsaid cylinder, and said cam-follower member being a post mounted on saidaxial extension.

5. Structure according to claim 4, said sleeve having a highly pitchedhelical edge engageable with said cam follower and having acircumferential extent approaching 360.

6. Structure according to claim 5, said cam member being free-floatingin said cylinder and said cylinder having a fixed second cam followerengageableagainst a straight edge on said sleeve to limit its rotationwithin said cylinder.

7. Structure according to claim 1 and additionally comprising clutchmeans automatically operated by operation of said power-applying fordiscontinuing the drive between the power supply for said sewing machineand said needlebar drive shaft upon operation of said positioning means.

8. Structure according to claim 7, said clutch means comprising at leastone friction member compressed between the driving pulley for saidneedle-bar drive shaft and means operable by movement of saidpower-applying means, the latter being a pneumatic cylinder alined withsaid shaft and mounted for slight reactive longitudinal movement duringenergization.

References Cited in the file of this patent UNITED STATES PATENTS1,181,363 Anschutz et al. May 2, 1916 1,470,687 Clarke Oct. 16, 1923FOREIGN PATENTS 375,597 France May 17', 1907

